Self-discipline, as human virtues go, is a pretty bloody annoying one. It has a pinched, goody-two-shoes, pleasure-denying air about it; it is the voice of the moralising teacher, or of the rightwing commentator who prescribes it as a remedy for every social ill but whose private life, one suspects, is a quagmire of neurosis and self-hate. Put it this way: you don't look forward to a big party at the weekend because you've been told all the self-disciplined people are going to be there. And yet – this is the annoying part – it's arguably by far the most important quality to cultivate. With enough of it, most desirable things (fulfilling relationships or work, happy moods, lots of money) are attainable; without it, none is. Even a committed hedonistic life requires plenty of self-discipline: you need it even to book the flight to Bali, to obtain those recreational drugs or to arrange the circumstances for wild sexual encounters. Otherwise inertia will out and you'll end up on the couch, half-dressed, watching reruns of Antiques Roadshow and eating baked beans. I speak, as ever, from experience.

It's with all this in mind that I've been testing the Pomodoro Technique, a productivity method that has recently achieved quasi-cult status online. Its originator, Francisco Cirillo, has been teaching it for 10 years, but it has now spawned several web-based fan groups and at least three iPhone apps. Adherents use words such as "godsend" to describe its effect on their ability to focus. In truth, it's unmiraculous, but then so are most genuinely useful things.

Here's what you do: you pick a task, then set a timer – a tool celebrated previously in this space – for 25 minutes, no exceptions. Cirillo uses a kitchen timer shaped like a tomato, and is Italian, hence "pomodoro". Work. When it rings, stop for five minutes. Repeat three more times, then take a longer break. That's just about it. Yet it works.

Half of all those reading that last paragraph will blink in confusion: "Why do you need a technique? Why can't you just do stuff?" But the rest of us know that such tricks can be hugely effective, slowly strengthening the self-discipline muscle. They are, literally, tricks: the ticking clock takes an internal desire to get something done and fools some part of the brain into thinking it's external, that the clock must be obeyed. (Stopping dead at 25 minutes also creates useful momentum for starting again five minutes later.) Even the hokey language – Cirillo calls each 25-minute period a pomodoro – helps, by making the time-blocks seem like "things", out in the world. Another geeky productivity scheme with an online following, Autofocus achieves something similar using cleverly structured to-do lists to "force" the user to confront the tasks they've resolutely been avoiding.

The illusion, voluntarily swallowed, is that choice has been removed – that there's something stopping you from choosing to abandon your focus and default to whatever inertia would have you do: daydream, websurf, beerdrink. Some people take this too far, establishing inner mental drill sergeants to yell at them all day, sapping the joy from life. Judiciously applied, though, this mental trickery is too useful a resource to ignore. Our brains are so easy to fool that it's borderline embarrassing; you might as well salvage some self-respect by exploiting that fact.